CEO. Although, perhaps say it in a neutral tone, with no bravado.
I always thought the title was a bit silly when running tiny start-ups.
But I missed an important point: Customers, Prospects, Recruits and Media like to talk to “the CEO”.
Even if it’s the CEO of a 5-person startup.
Customers, especially. They want to build a personal relationship with the CEO, the one person who is making a true commitment back to them on the 5+ year customer journey.
Use that title, at least externally.
Internally, if you prefer Founder, Chief Fixer, Trash Pickeruper, or whatever, understood. I did.